My co-sleeping experiences started when I myself was a baby. My parents did a lot of attachment parenting-type stuff before it was cool (Mom, you hipster, you!), and that included co-sleeping. My parents' picture albums are filled with lots of cute pictures of baby me cuddling up with my parents or with my brother, who is 22 months younger than me, in their big bed. I don't remember when I moved to my own bedroom, but I do have some funny early memories of going to my parents' bedroom in the middle of the night and standing there, waiting for an invitation to come into bed with them. When my parents, sound asleep, of course, failed to notice my presence, I'd start making little fake crying sounds until one of them said, "Maria, is that you? Come on in..." My mom says one time I just said "Ahem!" loudly until they noticed me! I wasn't trying to be manipulative; little kid me just felt alone sometimes at night and needed the security, but didn't want to be rude and just jump into bed with my folks. I was a strange child. :-D
Now, I don't know if this is related to co-sleeping at all, or if I just have awesome sleep genes, but I'm one of the best sleepers I know-- insomnia is a SUPER rare occurrence with me, and I fall asleep very quickly at night. My friends will attest that I can usually take a nap anywhere at any time I want. All my early memories of sleep are very positive and warm, and I think that stays with me to this day.
So here is living proof that no, co-sleeping kids don't sleep with their parents forever; that yes, parents can still, um, have marital relations (I have four younger siblings, for crying out loud); that no, co-sleeping is not setting your kid up for awful sleep habits; and that no, co-sleeping won't make your kid weird for life. Well, the jury is still out on that last one.